Device for preventing overtravel of operating mechanisms



Nov. 23, 1948. I A. c. DAVIS DEVICE FOR PREVENTING OVBRTHAVEL OF OPERATING IECHANISIS Filed larch 9', 1945 d 19 27'? 9 I %L f I 72 9 JPUMP Patented Nov. 23, 1948 DEVICE FOR BREVENTING OVERTRAVEL OF OPERATING MECHANISMS Alan C. Davis, East Haddam, Conn.

Application ll larch 9, 1945, Serial No. 581,864

The present'invention relates to a device to be used in conjunction with a temperature or pressure responsive instrument such as a switch or valve to eliminate excessive movement 01' parts thereof which might result in damage to the instrument.

Specifically, the device includes a'single manually operated nut carried by the operating part of the control instrument to calibrate the part: overtravel limitations is also accomplished by the nut, preventing damage to the instrument parts; and excessive movement of instrument parts caused by pressure pulsations in the fluid system is prevented by the nut and its associated structure.

Another object of the invention is to provide a device of this character which may be readily adapted for use on mechanisms where the use oi control devices is desired.

Other objects of the invention will be apparent from the following description of the present preterred' form of the invention. taken in connection with the accompanying drawings, wherein:

Figure 1 is a side elevation of a device constructed in accordance with the present invention illustrating its application, parts thereof being shown in section to disclose details; and

Figure 2 is a perspective view of the calibrating nut of the present invention.

In order to illustrate the application of my invention. 1 have in Figure 1 shown diagrammatically an internal combustion engine 3 and a pump ti, the engine and pump being incommunication with a pressure lubricating line it. the latter having tapped thereinto a branch line t. The branch line in turn communicates with a spring loaded flexible bellows, generally designated i, which may be of standard construction. The spring of the bellows, indicated at d, is convoluted about a sleeve or bushing 9, which latter is carried by a casing wall it oi'the pressure responsive device. One end of the spring 8 engages said wall while the opposite end engages adisc it secured to one end oi the bellows 7, the disc being equipped with a shaft i ii. The shaft ltextends through the bushing t and wall i0, its

outer end being screw-threaded as indicated at it.

The inner face of the wall it carries a frame generally designated it, the inner terminal of which carries an abutment or barrier I5. In

some cases the wall it may act as the lower barrier. The frame also includes an abutment or barrier it which. extends in parallel relation to the intermediate part of the abutment l5 and the wall it, the abutment it being provided with 2 Claims. (01. 137-158-i5) an opening i7 through which theshait l2 extends. The abutment i8 is also provided with an opening indicated at It which is in alignment with the opening l1, and the axis of bushing 9.

The threaded end of the shaft I2 is adapted for engagement by a complementally threaded nut it one end of the latt'erbeing of larger diameter than the diameter of the opening indicated at H. The opposite end 20 of the nut is of considerably smaller diameter and is engaged through said opening M. f

As set out above, and shown to advantage in Figure 2, the end of the nut 01 larger diameter is provided with a screw-threaded recess with which a setscrew 2i communicates, in order that the nut may be held in a fixed position on the shait it when desired. The extreme outer terminal of the smaller diameter and 20 of the nut is closed. for a purpose hereinafter set forth.

Also mounted on the frame it is a switch mechanism generally designated 22. a moving. part it oi which engages the closed outer terminal of the smaller diameter'end 20 of the nut. Movement of the nut through the abutment i8 effects movement of the element 23 for a. purpose which will be presently described.

Reduction or increase in the pressure 01' the lubricating oil passing through the line 8, to a predetermined value, results in a corresponding reduction or increase in pressure in the bellows. permitting the latter to be collapsed under the expansive force of the spring ii. if the pressure decreases, or to expand against the thrust of said spring ii the pressure increases. Correspondingly. theshaft it, carried by the bellows, moves toward the oil pressure line b if the pressure decreases, or' away from said line if the pressure increases, automatically efiecting operation of the moving part 23 of the switch 22, resulting in the performance of some predetermined iunction designed to give warning of an undesirable condition or to prevent damage to the engine. This function may be to give a visual and/or auricular signal or may set in motion other mechanism to 3 ment life due to elimination of bellows movement under pulsating pressures in the fluid system to which the instrument is connected, as follows:

1. Calibration is accomplished by manually adjusting the nut I9 on the shaft l2 and securing it, if desired, at the predetermined point of adjustment, by means of set screw 2|.

. 2. Overtravel of the moving parts of the assembly which would cause damage to the switch, and distortion of the. bellows or diaphragm, which would cause change in instrument calibration or bellows or diaphragm failure is prevented, since the extent of movement of the shaft I2 is limited by the abutments l5 and I6; and

3. Rapid flexing of the bellows or diaphragm which would be caused by pulsating pressures in the fluid system at pressures above or below the calibrated setting of the instrument is also prevented, by reason of the limited travel allowed the nut I9 between the abutments l5 and I6. Rapid flexing of the bellows or diaphragm due to pulsating pressures in the fluid system not otherwise prevented, would result in very early failure of the bellows or diaphragm, due to fatigue of bellows or diaphragm material.

While I have herein described a preferred form of the invention, it is nevertheless to be understood that various changes may be made within the scope of the claims hereto appended.

What I claim is:

1. In a pressure or temperature responsive device, parallel abutments, a threaded shaft and a nut, the threaded shaft extending throughone of the abutments and engaged with the nut, an

end of the nut being extended and engaged through the other abutment, and mechanism engaged with the extended end of the nutand operable upon movement of the latter.

2. In a pressure or temperature responsive device, a frame equipped with fixed abutments, a sprin operated shaft extending through one of said abutments, a nut threaded on the shaft, one end of the nut extending through the other abutment, the nut being adjustable on the shaft to adjust its extent of travel between the abutments, theextended terminal of the nut being adapted for engagement with a part to be moved.

ALAN C. DAVIS.

REFERENCES CITED The following references'are of record in the file of this patent:

UNITED STATES PATENTS 

